The NYPD may have caught the attempted Times Square car bomber on tape-and is hoping a $24m phalanx of cameras can stop future attacks. But the track record of large, metropolitan surveillance networks pre-empting terrorists is weak, at best.

In 2006, the New York Police Department announced a three-year, $106 million plan that promised to prevent attacks on New York's financial district with a web of license plate readers, chemical sniffers, radiation detectors, and 3,000 publicly- and corporately-owned cameras. All the information would then be channeled into a single coordination center. Specialized video intelligence algorithms would be used to spot would-be attackers as they case their targets. "This is about identifying and eliminating a threat, rather than dealing with the consequences," NYPD assistant chief John Colgan told me as planning for this Lower Manhattan Security Initiative got under way. "I'm not in the consequence-management business."

Today, the LMSI's coordination center is up and running. Some cameras are now keeping watch over the financial district. But according to the grant request, the installation and integration of many of those cameras is running far, far behind the initial three-year deadline. The NYPD says it aims to "install all camera systems at designated locations" between January 1st of 2011 and July 31st of 2012. It also wants a "video surveillance system and collaboration portal" to integrate feeds from old and new cameras by 2012 - three years past the original goal. By the middle of this year, the Department wants to "acquire and install CCTV cameras and all Coordination Center equipment," as well as "acquire, install and implement all software programs…. [and the] hardware to run systems' software."

Of course, today's bombers know that city spycams are only used for forensic purposes - finding the bomber, after the bomb has gone off. Attitudes could change, if the video feeds can be integrated and upgraded with the kind of algorithms banks and casinos use to keep tabs on their customers. But to the best of my knowledge, no city has been able to pull such a system off, yet. Banks and casinos have consistent lighting, and access to every nook to position a camera. Citites don't. The challenges of open air, mass surveillance of people are still too great.

New York is hoping to be the first to pull it off. And not just with the LMSI, but with the recently-announced Midtown Manhattan Security Initiative, too. The idea is to blanket "key locations between 30th and 60th Streets from river to river" with spycams and license plate readers. According to the grant documents, the NYPD would like to complete a "study of the area to determine locations for surveillance assets" by July, 2012. As the same time, New York officials also want to set up a "dedicated… network… to handle all data sources as previously identified to expand this security initiative into midtown Manhattan. Once established, the network will provide virtually unlimited bandwidth and access to the cumulated data."

The most useful data may be the simplest to obtain and to share. License plate numbers are much easier to recognize than human faces. The technology to pick out a suspicious number is time-tested. Which is why a key component of New York expanded surveillance ring "is to reduce NYC's vulnerability to an IED attack through a comprehensive domain awareness program focused on key bridges, tunnel, infrastructure and vehicles entering the Lower and Midtown Manhattan zones," the NYPD notes in its grant request. "Each License Plate Recognition System can scan thousands of cars per day and will alert Police Headquarters to the presence of a suspicious vehicle. This capability provides the NYPD with early warning capability to support investigation and interdiction."